In the waterproofing industry many coating systems are applied with rolled fabric embedded in the coating to reinforce seams or cracks in the existing substrate. Generally, this is performed on a smooth surface where directly unrolling the fabric and removing any wrinkles on the roll is relatively easy and “straight forward”. However, there are other surfaces like a metal deck, where the surface profile is more complex, an as a consequence the process of applying the fabric is time consuming. Moreover, to make it worst even with a light wind, this process becomes extremely difficult and almost impossible to perform without sacrificing the quality in the final product.
Many styles of surface profiles are currently available on the market provided by different manufacturer with different specifications. Also, there are instances where the profiles can differ dimensionally (even on the same site) sometimes due to poor handling during installation and/or foot traffic after the installation.
There are two methods commonly used in the market to perform the coating operation:
Method 1
This method is generally slow and labor intensive. In this method, coating is applied to the deck by either: a brush, a roller or spray equipment. The fabric is then unrolled and placed in the coating, where immediately 2 or 3 workers will resolve and/or brush out the wrinkles. An additional worker recoats the fabric and it is then allowed to dry.
Method 2
The second method although quick, typically has reduced surface quality, and has a number of safety issues in terms of full OSHA compliance. In this method a worker sprays directly from overhead applying the coating to the substrate. While the substrate is still wet, a second worker walks quickly backwards (almost running) unspooling the fabric directly over the profile. Simultaneously, the original worker sprays the fabric down over the profile with the force of the spray to effectively recoat the fabric. This complete operation must be closely coordinated so that the original layer of coating does not dry before embedding the fabric and the unrolling and re-spraying of the fabric must happen within 8 inches to 12 inches of each other. Finally, single directional spraying over a multi-angled profile does not allow for an even coating application.
In the coating application field, whether in roof coating or car painting, the key is a timely, even coat that sufficiently covers the entire surface. Most people will typically refer to a proper “application technique”, particularly when discussing spray applications (but viable with rollers, and brushes as well). Even for those people knowledgeable and experienced about the proper application technique is almost impossible to maintain that level of technique throughout the day because of various obstacles, physical tiredness and lack of concentration. Average variances of up to 400% have been found on single jobs with instances of even greater variance.
Attaining a high and constant precision application as reasonable under the existing conditions is particularly important in the waterproofing field, because except for specific circumstances, the applied waterproofing will wear off/deteriorate at the same rate across the entire exposed surface. So, an uneven application will reach full deterioration sooner in the thinner locations yet delayed (with arguably wasted coating product) at the thicker locations.
To better understand the importance of attaining a high and constant precision application lets first look at some of the variables that might occur during a typical application.
Brushes/Brooms
Using brushes and brooms greatly slows down the process and will limit the area covered. Also, more already dried edges are accumulated that will in turn get recoated and the coating build up is thus, doubled. Add to that the fact that natural contours are left by the bristles (ranging depending on the quality), and a truly uneven surface application is achieved.
Rollers
Rollers, although probably quicker than using brooms (and thus less of the edge drying/recoating condition) also leave a “textured” finish. The final product would look something like the moon surface with craters and ridges, not necessarily dramatic to the eye, but radically disproportionate with 3 mils (dry) in the craters and typically 7-9 mils (dry) on the ridges.
The recent desire to maintain highly reflective roofs and building exteriors is also hindered by this texture since dirt and moisture are retained in the craters reducing the long-term reflectivity of the installed waterproofing. Additionally, the typical installation leaves twice as much coating following the saturation of the roller leading up to the worker deciding if more paint on the roller is needed.
Hand Spraying
Spraying by hand resolves a number of the previously explained issues. There is less texturing, the work progresses quickly so there is less overlapping on an already dries edge, and a worker that can maintain a good spray technique can apply a reasonably even coat to approximately 15,000 square feet per 8 hour period. The problem is that this technique must be maintained for the full 8 hours. One of the most common variables encountered with this technique is the tip distance to the application surface. This variance happens in many forms as a worker swings the gun side to side the extended distance to the surface must be accounted for. If the gun is swung front to back the spray “fan” becomes close on one side (edge) than the other. If a rib profile is sprayed from the side, the opposite side of the rib is shadowed, if a rib is sprayed from directly overhead (downward) the taper of the rib profile and the ever expanding “fan” from the spray tip interact to apply less paint on the sides of the rib compared to other areas (in fact there will also be naturally more paint on the flat top surface of the rib, than the flat surface of the roof deck directly below). These events coupled with wrist fatigue (fighting with 3000 psi coating ejection at the tip), maintaining concentration over a long period of time and under rough weather conditions, and normal human error adds up as accumulated variance.
Thus, what is needed is an efficient and easy-to-operate apparatus and a method for quickly applying a sheet of fabric across a surface of a roof deck using the same.